No, the text field is called "Allowed browser exam keys" because Browser Exam Keys can be pasted there, and not Config Keys. Currently Moodle only uses the Config Key it calculates from a Moodle-generated ("Configure manually") or uploaded ("Upload my own configuration") configuration. The idea of the Config Key is, that it doesn't have to be copy-pasted manually (if that wasn't clear from Moodle documentation page, I guess it should be clarified there).
That's the reason why I answered the original question of this thread: Why doesn't the Config Key check work and that error message is displayed.
That's the reason why I answered the original question of this thread: Why doesn't the Config Key check work and that error message is displayed.